The Differences Between a 426 Hemi and a 426 Wedge

Since both engines are iconic and share the same cubic inches, many people ask about their differences. Let’s answer, what is the difference between a 426 Hemi and a 426 Wedge?

The main difference between a 426 Hemi and 426 Wedge is the cylinder head design. Hemi has a hemispherical combustion chamber and the Wedge a wedge chamber. Both engines have different blocks, cams, compression ratios, intake and exhaust manifolds, carbs and valve trains.

This article will dive into the details about each difference, including the horsepower and torque numbers.

The Differences Between a 426 Hemi and a 426 Wedge Engine

To understand the difference between the two engines, let’s examine the different 426 Hemis and 426 Wedges.

There are two different race Hemi engines, Track (Nascar) and Drag (NHRA). Then, of course, is the street Hemi.

There are two different Wedge engines, the Max Wedge and the Street Wedge. The Max Wedge became the common term, but it was originally called the Maximum Performance Wedge.

The race Hemis were introduced in 1964 and ran in race cars for Nascar and for the NHRA at the drag strips. The street Hemi was produced from 1966-1971.

The 426 Max Wedge could be ordered in 1963 and 1964. It was basically a 413 Max Wedge with 13 more cubes. It ruled the drag strips prior to the Hemi engine.

The Plymouth versions of the Max Wedge were called the following:

Super Stock 426
Super Stock 426-ll
Super Stock 426-lll

The Dodge versions were called the following:

Ramcharger 426
Ramcharger 426-A
Ramcharger 426-lll

Other common names for the engines are “Stage ll” and Stage lll.” There was never a Stage 1 although people refer to the first version by that name.

Lead by Chrysler engineers, the team “Dodge Ramchargers” took on everybody at the strip and made a ton of new track records with the Wedge cars.

It was the Max Wedge which put Chrysler on the map as a force to be reckoned with on the strip and the street.

The street Wedge was produced in 1964 and 1965.

Of course the race Hemis and the Max Wedge engines were developed for one purpose only, racing.

The street Wedge and Hemi engines were detuned versions and developed for use on the street for the “daily drivers” of the day. Even though they had less horsepower, they were considered hot cars for the street.

Let’s examine the differences between the two engines in more detail.

1964 Plymouth Super Stock 426 lll Max Wedge in a Plymouth advertisement. — 1964 Plymouth Super Stock 426 lll Max Wedge in a Plymouth advertisement

Cylinder Heads

Probably the biggest difference between the two 426 engines is the cylinder head design. The cylinder heads are also what gives each engine their names.

The Hemi has hemispherical combustion chambers, and the Wedge has wedge chambers.

The Wedge engine has the intake and exhaust valves inline with each other, parallel with the camshaft. The Hemi has the valves opposite each other.

The Wedge valves face straight down, The Hemi valves face down at an angle.

The Wedge combustion chamber is flatter and not as deep as the domed Hemi chamber. The larger chamber and angled valves allow the Hemi to have larger valves.

The Hemi has 2.25″ intake valves and 1.94″ exhaust, both larger than the Wedge. The Max Wedge has 2.08″ intakes and 1.88″ exhaust. The street Wedge has 2.08″ intakes and 1.60″ exhaust.

Engine	Valve Sizes
All 426 Hemi Engines (1964-1971)	2.25″ In/1.94″ Ex
426 Max Wedge (1963-1964)	2.08″ In/1.88″ Ex
426 Street Wedge (1964-1965)	2.08″ In/1.60″ Ex

Comparing the 426 Hemi, 426 Max Wedge and 426 Wedge engine valve sizes.

A Hemi head intake and exhaust ports are larger and in a straighter path than the Wedge, allowing the air to pass with less disturbance. A Wedge engine’s ports are smaller and opposite each other with more bends.

A Hemi engine has the tip of the spark plug located in the center of the chamber while a Wedge has the spark plug tip to the side.

For a complete breakdown of all 426 Hemi head casting numbers, check out my article, 426 Hemi Head Casting Numbers.

Valve Train

Due to the different head and valve designs, the valve trains also differ greatly.

Since the Hemi intake and exhaust valves are opposite each other, the rocker arms pivot on two rocker shafts instead of one.

A Wedge has the intake and exhaust rocker arms on one shaft because the valves are in a straight line parallel with the cylinder heads.

The rocker arms are also different styles shown in the picture below.

426 Hemi and Wedge Block

Even though both blocks share the same cubic inches, bore and stroke, the similarities end there.

The Hemi block has 4 bolt mains while the Wedge has 2 bolt mains. The middle three main bearing caps in the Hemi have two additional bolts cross threaded in from the sides of the block.

The Hemi block has cast-in bosses leading down into the valley for additional head studs secured with nuts from underneath. The Wedge didn’t have these, and the heads are secured with all bolts from the top.

The Hemi also has oil return passages on the deck surface which the Wedge doesn’t have.

The Hemi engine mounts are different than the other Mopar big blocks. For this reason it requires a K-frame unique to the engine.

The Max Wedge blocks have exhaust valve reliefs (bore notches) at the top of the cylinder bores to clear the 1.88″ exhaust valves. The Hemi or street Wedge does not have bore notches.

For more detailed Hemi head characteristics check out my article, How to Identify a 426 Hemi.

Compression Ratio

The race Hemi has 12.5:1 compression and the street Hemi has 10.25:1 compression.

The 1963 Max Wedge engines has either 13.5:1 or 11:1 compression ratios. In 1964 it was available with either 12.5:1 compression or 11:1.

The 1964 and 1965 street Wedge engine is much tamer with a 10.3:1 ratio but slightly higher than the street Hemi.

Engine	Compression Ratio
426 Race Hemi engines	12.5:1
426 Street Hemi (1966-1971)	10.25:1
426 Max Wedge (1963)	13.5:1 or 11.0:1
426 Max Wedge (1964)	12.5:1 or 11.0:1
426 Street Wedge (1964-1965)	10.3:1

Comparing the 426 Hemi, 426 Max Wedge and 426 Street Wedge engine compression ratios.

Connecting rods

The Hemi has heavier and longer connecting rods than the Wedge engines.

The Hemi rod measures 6.861″ center to center. The shorter Wedge rod measures 6.768″ center to center.

Camshafts

The camshafts are different for each Hemi and Wedge engine. The race Hemis has the most aggressive cams of the bunch. The street Wedge has the milder cam.

The Max Wedge engines have a mechanical cam and the street Wedge a hydraulic cam. All the Race Hemis has a mechanical cam. The street Hemi had a mechanical cam early on switching to a hydraulic one in 1970.

Engine	Cam Lift	Cam Duration
426 Race Hemi “Track”	1964-65: .540″ 1966: .565″	1964-65: 312° 1966: 328°
426 Race Hemi “Drag”	1964: .520″ 1965: .540″	1964: 300° 1965: 312°
426 Hemi Street	1966-67: .467″/.473″ 1968-71: .490″/.481″	1966-67: 276° 1968-71: 284°
426 Max Wedge	1963: .509″ 1964: .520	1963: 11:1 CR: 300/300° 1964: 12.5 CR: 300/308°
426 Street Wedge	1964-65: .430″	1964-65: 268°

Comparing camshaft specs between the 426 Hemi, 426 Max Wedge and 426 Wedge engines.

Intake manifolds

The track Hemi (Nascar) has a bathtub single four barrel manifold and the Drag Hemi (NHRA) has a dual four barrel cross ram manifold which mounts the carburetors diagonally across. In ’64 they were aluminum and magnesium was used in 1965.

The street Hemi has a dual plane aluminum intake manifold which mounts two four barrel carburetors inline with each other.

The 426 Max Wedge has a dual four barrel cross ram which mounts the carburetors diagonally across from each other.

The street Wedge has a cast iron single four barrel intake with a heat crossover for cold starts. The street Hemi has openings in the rear to allow heat from the exhaust to enter underneath the rear carburetor.

Carburetors: Wedge, Race Hemi and Street Hemi

The street Hemi has two four barrel Carter carburetors, 625 cfm each, mounted inline (tandem).

The race track Hemi has one four barrel Holley carburetor.

In early 1964, the drag Hemi had two four barrel Carters, 750 cfm each. Later in ’64, once they perfected the Holley, they switched to two four barrel Holleys, 770 cfm each. They are mounted diagonally across from each other.

All the 426 Wedge engines used Carters. The Max Wedge had two four barrels, 525 cfm in ’63 and later in ’63 and ’64 they increased to 750 cfm. They were mounted diagonally across from each other.

The street Wedge has a single four barrel Carter, 575 cfm.

Engine	Carburetors
426 Max Wedge (1963)	2 Carter Four Barrels 525 cfm each
426 Max Wedge ll (Later 1963 & 1964)	2 Carter Four Barrels 750 cfm each
426 Street Wedge (1964-1965)	1 Carter Four Barrel 575 cfm
426 Street Hemi (1966-1971)	2 Carter Four Barrels 625 cfm each
426 Track Hemi (Nascar)	1 Holley Four Barrel
426 Drag Hemi (NHRA) (Early 1964)	2 Carter Four Barrels 750 cfm each
426 Drag Hemi (NHRA) (Later 1964-1965)	2 Holley Four Barrels 770 cfm each

Comparing the 426 Max Wedge, 426 Wedge and 426 Hemi carburetors.

426 Exhaust manifolds

The street Hemi has high flow exhaust manifolds which curves down and towards the rear. The right side manifold has a heat riser to help the daily driver with cold starts.

The race Hemis all uses header style manifolds.

The exhaust manifolds on the ’63 Max Wedge and the ’64 and ’65 street Wedges are unique. Each tube curves up and towards the rear.

The ’64 Max Wedge manifold also curves up but more pronounced with initial equal length tubes for each cylinder. Willem Weertman, in his book Chrysler Engines 1922-1998, called it a Medusa-like tangle of cast iron.

The Max Wedge exhaust system came with Lake pipe caps (cutouts) after the collector so the exhaust can be uncorked for racing use.

Both engine manifolds were designed to have a high exhaust flow.

Oil Pickup Tubes

The Max Wedge and Hemi both have 1/2″ oil pickup tubes. The difference is the 1963 and 1964 Max Wedge has a swinging pickup.

Comparing the 426 Max Wedge and 426 Hemi oil pickups. — Comparing the 426 Max Wedge and 426 Hemi oil pickups

The pickup swings to the rear under hard acceleration and forward upon heavy deceleration to stay with the transfer of the oil in the pan.

Horsepower and Torque: Wedge and Street Hemi

The following table compares the horsepower and torque between the Hemi and Wedge engines.

Engine	Horsepower Torque
426 Max Wedge (1963-1964) 11:1 CR	415 hp @ 5,600 rpm 470 ft lb @ 4,400 rpm
426 Max Wedge (1963) 13.5:1 CR	425 hp @ 5,600 rpm 480 ft lb @ 4,400 rpm
426 Max Wedge (1964) 12.5:1 CR	425 hp @ 5,600 rpm 480 ft lb @ 4,400 rpm
426 Street Wedge (1964-1965) 10.3:1 CR	365 hp @ 4,800 rpm 470 ft lb @ 3,200 rpm
426 Street Hemi (1966-1971) 10.25:1 CR	425 hp @ 5,000 rpm 490 ft lb @ 4,000 rpm

Comparing the 426 Max Wedge, 426 Street Wedge and 426 Hemi Horsepower and torque specs.

At first glance the Hemi and Max Wedge are rated at the same horsepower, 425 hp. Let’s examine this a little closer and determine why the 426 Hemi is superior in power to the Max Wedge.

The 426 Hemi is superior due to its higher horsepower at 5,600 rpm and cylinder head design. Revving the Hemi 600 rpm higher results in a higher horsepower number than 425 hp.

The advertised Wedge’s power is rated at 5,600 rpm while the Hemi at 5,000 rpm.

426 Wedge horsepower on the dyno.

As noted in my article, 426 Hemi Rated and Real HP, an all original street Hemi without a rebuild, was hooked to a dyno and had 452 hp @ 5,500 rpm. This was a worn engine with a smaller cam and lower compression than the Max Wedge.

The Max Wedge has 13.5:1 compression compared to the street Hemi’s 10:25:1 ratio. The Max Wedge also has a much larger camshaft than the street Hemi.

I’m not knocking the Max Wedge at all, just saying there is a reason Top Fuel Dragsters today have a Hemi designed engine. While I drive around in the street, I personally prefer a 426 or 440 wedge engine for its kick in the pants low-end torque.

426 Max Wedge Intake and heads horsepower on the dyno.

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For the past 40 years, I’ve been studying and researching Mopar engines like the 426 Hemi and max wedge. I’ve assembled engine parts, read books, articles, magazines, watched videos, attended seminars and spoken to other Mopar experts.